Trunk Exoskeleton with Angle-Dependent Torque for Bending Support
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Solution Overview
Problem
Existing back support devices fail to differentiate between walking and bending, leading to uncomfortable and hazardous use, as they provide resistance during both activities, restricting movement and preventing comfortable walking and sitting.
Innovation Solution
A trunk supporting exoskeleton with first and second thigh links and a supporting trunk, featuring torque generators that impose resisting torque only when the wearer bends forward beyond a predetermined angle, allowing for unrestricted walking and sitting by distinguishing between walking and bending through minimal sensing and hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If passive spring resistance is used to create torque during bending, then the bending moment on the spine is reduced, but the device provides resistance during walking and sitting as well, making movement uncomfortable and hazardous
Solution Approach 1:
The patent employs a dynamic control system that adjusts torque generation based on real-time detection of user activity. Sensors detect whether the user is bending or walking, and the torque generators actively modulate resistance accordingly. This resolves the contradiction by making the support strength adaptive - providing maximum support during bending while eliminating resistance during walking, thereby improving both back protection and movement comfort.
Solution Approach 2:
The system incorporates feedback mechanisms through sensors that continuously monitor user posture and movement state. This feedback loop enables the control system to distinguish between bending and walking activities, adjusting torque generation in real-time. The feedback principle resolves the technical contradiction by ensuring the device provides appropriate support only when needed (during bending) while remaining inactive during normal activities like walking, thus improving both spinal protection and ease of movement.
2Reliability
If passive spring resistance is used to counteract trunk gravity weight, then the L5/S1 spine area injury risk is reduced, but the user cannot move around unrestricted since legs must push against the devices during walking and sitting
Solution Approach 1:
The patent transforms the static passive spring system into a dynamic active system that adapts its torque generation based on detected activity type. During bending, the system provides strong supportive torque to prevent injury; during walking or sitting, it reduces or eliminates torque to allow free movement. This dynamic adaptation resolves the contradiction between injury prevention reliability and movement freedom by making support conditional rather than constant.
Solution Approach 2:
The system uses sensor feedback to detect whether the user is performing bending or locomotive movements. Based on this feedback, the control system selectively activates or deactivates torque generation. This feedback mechanism enables the device to maintain high reliability during bending while preserving movement freedom during walking and sitting, effectively resolving the technical contradiction between these two opposing requirements.
3Strength
If the exoskeleton provides resistance during both bending and walking, then back support is maintained, but the device complexity increases and user comfort decreases
Solution Approach 1:
The patent implements a dynamic control strategy that switches between different torque generation modes based on activity detection. Rather than providing continuous passive resistance, the system actively modulates torque output - providing support during bending and reducing resistance during walking. This dynamic approach maintains adequate back support while simplifying the control logic compared to systems that must manage continuous resistance across all activities, thereby resolving the contradiction between support strength and device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The exoskeleton effectively reduces muscle forces in the back during forward lumbar flexion, enabling comfortable walking and sitting without constraints by providing support only when needed, thus reducing the risk of injury and improving user mobility.
Implementation Method 1
a resilient pendulum comes into contact with an engagement bracket, causing a resisting torque between the supporting trunk and a respective thigh link
Data Source
AI summary
An exoskeleton includes two torque generators, thigh links, and a supporting trunk rotatably coupled to the thigh links. When a wearer bends forward in the sagittal plane such that the supporting trunk extends beyond a predetermined angle A with respect to vertical, at least one of the torque generators imposes a resisting torque between the supporting trunk and a corresponding thigh link, thus imposing a force onto a wearer's trunk and thighs to aid in supporting the wearer in a bent position. The torque generators may be active or passive torque generators. When the supporting trunk does not extend beyond the predetermined angle A, the torque generators do not impose resisting torques between the supporting trunk and thigh links during the entire range of motion of the thigh links, thus enabling a wearer to walk, run, and sit without constraint while in a substantially upright position.